Air springs, or pneumatic suspension devices, have long been used to isolate road disturbances from a vehicle, seat, or cab. An air spring, as part of a vehicle's suspension, supports the vehicle's load or mass at each axle. Typically, each axle of a vehicle associated with an air spring supports the mass component or load carried by the axle. In addition, there may be ancillary air springs that support driver comfort in and around the driver's compartment, or cab. In an air spring, a volume of gas, usually air, is confined within a flexible container. As an air spring is compressed (jounce travel), the pressure of the gas within the air spring increases; and as an air spring extends (rebound travel), the pressure of the gas within the air spring decreases. Road disturbances are mainly absorbed by this compression and extension of the air springs as a function of work (w=∫F·dx). Air springs are often engineered to have a specific spring rate or spring constant, thereby controlling jounce and rebound characteristics for the desired application and for comfort.
Because an air spring may undergo countless cycles between compression and extension, the air spring must include an enclosure container for the gas that is flexible and durable. Typically, these enclosures are referred to as bellows or airsleeves and are made of cord-(fabric or metal) reinforced rubber compositions. Cord-fabric may be, but is not limited to, natural or synthetic materials.
As those skilled in the art appreciate, efforts to improve the emissions from trucks or other transportation vehicles that may be equipped with air springs has resulted in, among other things, higher operating temperatures for the engines of these vehicles. Unfortunately, however, these higher temperatures have placed higher demands on those air springs that are located near the engine or the exhaust from the engine. In particular, the operating temperature of the air springs has likewise increased, which has resulted in a reduced service life of the air spring, particularly the bellow. Likewise, vehicles equipped with air springs often operate in cold environments, which necessitate that the bellows have a useful low temperature operating window as well.